Influence of Pylon Air Loads and Composite Tailoring On Aeroelastic Stability of Folding Tiltrotor Aircraft in Cruise Flight
Open Access
- Author:
- Slaby, Jason
- Area of Honors:
- Aerospace Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. Edward Smith, Thesis Supervisor
Dr. Edward Smith, Thesis Supervisor
Philip John Morris, Thesis Honors Advisor - Keywords:
- Aeroelastic Stability
Tiltrotor
Composite
stop/fold - Abstract:
- The presence of a folded rotor pylon on the end of the wing for a stop/fold rotorcraft had an effect on the structural response at high speed cruise. A forward swept wing would be required for the stopping and folding process as well as the high speed flight. Divergence velocity of a forward swept wing can be greatly decreased in a standard metallic isotropic wing structure because the bending will cause the angle of attack to increase cause a feedback of bending and twisting. The addition of the rotor pylon influenced the lift and drag to the wingtip depending on the shape and placement of the pylon. The shape of the pylon on the wing tip was found here to have a greater influence on the divergence velocity than the location of the pylon relative to the wing. Changing the shape of the pylon decreased the divergence velocity by over 15% while changing the location of the pylon only affected the divergence by 4%. The addition of the pylon drag on the deflecting wing caused a torque that had the largest influence on the divergence velocity from the pylon. Depending on the sweep of the wing the drag force reduced the divergence velocity from 25%-60%. Composite tailoring was used to lessen the loss by inducing a bending-torsion coupling in the opposite direction by stiffening the structure off axis. The main concern of the composite tailoring was to maintain the bending and torsional stiffness on the wing. When composite tailoring was included, while maintaining the effective stiffnesses, the divergence velocity was maintained at a value greater than the loss from the lift or drag caused by the pylon. The flutter velocity of the stop/fold rotor was also greatly influenced by the presence of the folded rotor pylon. Unlike divergence the forward sweep on the wing helps the flutter speed. Moving the center of gravity of the pylon caused a decrease of the flutter velocity as high as 60%. It was discovered that if the center of gravity of the pylon was moved far forwards the pylon could be used to effectively mass balance the wing and increase the flutter velocity.